QGIS aims to be an easy to use GIS, providing common functions and
features. The initial goal was to provide a GIS data viewer, but now
it also permits to edit, create and analyze lots of spatial datas.
QGIS supports a number of raster and vector data formats, with new
support easily added using the plugin architecture.
Supported formats are :
- spatially-enabled PostgreSQL tables using PostGIS.
- most vector formats supported by the OGR library, including ESRI
  shapefiles, MapInfo, SDTS and GML.
- raster formats supported by the GDAL library, such as digital
  elevation models, aerial photography or landsat imagery.
- online spatial data served as OGC-compliant WMS or WFS.
